Ok. I'm in the process of having my 1939 Hudson 112 restored. Of course this car is originally 6 volt positive ground, right? The shop has it hooked up as 6 volt negative ground. When I questioned this, they said the only thing they would have to do to change it would be to change the polarity of the generator. Is that right? I know the lights don't really care, but do all the instruments, gas gauge, radio, etc not really care? It seems I read somewhere once that it is harder on the points to be negative ground than positive ground. Is that true? I think I just need to tell them to correct it to be original. What does everybody know? What advice can you give? Thanks ! Mike Sheridan
Nothing's polarity sensitive except the coil and some original vacuum-tube radios. The generator can get its polarity reversed by merely "flashing the field." The shop knows how to do that . . . very simple.. If the coil isn't connected properly, you'll lose about 15% of your spark voltage.
Won't the starter spin the wrong way? Seems simpler to keep is original and +ive ground than worry about the coil etc.
No, the starter won't spin the other way. I'd change the system back too, just for originality, but it's no big deal to leave it alone if that's preferred.
Ok, thanks Park. I'll get it corrected. Mike Sheridan
Mike,
That could bring about some real "drama" at the shop. I hope that the restoration is going as planned.
John
John - The restoration is nearly done. I'll have it at the National. This is a minor bump in the road.
What would be the reason behind reversing the polarity? It works perfectly well the original way.
Eddie - We've now been negative ground so long that younger people don't even consider that it would have been any different on some cars.
Maybe, since everyone eventually went to negative ground, they thought there was some advantage to doing so.
I had heard that when Delco got such a big piece of the automotive "pie", that they wanted to standardize everyone, and got most manufacturers on the negative ground. Once the majority was there, the rest followed. Not sure if this is automotive urban legend or not.
[quote="Eddie Adler" post=10704]What would be the reason behind reversing the polarity? It works perfectly well the original way.
I was talking about the shop doing the work. Not why the auto makers switched.
There is a reason why cars used positive grounds but I can't remember why There is also a reason why cars went to negative grounds when they went over to 12 volts. I don't remember that reason either. 😆
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